The invention relates generally to a saddle conveyor for use in signature handling systems. More specifically, the present invention relates to a tilting chain for a saddle conveyor which allows access to the bottom of the folded edge or backbone of a signature from beneath the saddle conveyor.
A saddle conveyor has been used to move the signatures between a number of operation stations. The stations may have various functions such as collating and/or stitching. A saddle conveyor collects the signatures, carries them between the various stations, and finally locates them for transfer to another conveyor.
One known method of conveying signatures includes pushing the signatures along a stationary saddle shaped like an inverted "V". At its apex the inverted "V" has a channel in which pusher fingers are reciprocated to incrementally advance the signatures on the saddle. See, e.g., U.S. Pat. No. 3,366,225. In such system the backbone of a signature has not been accessible from below to devices for acting thereon.
Conveyor systems are known in which the bottom of the backbone of a signature has been accessible. Examples are shown in U.S. Pat. Nos. 937,925, 1,400,725 and 3,786,979. in U.S. Pat. No. 937,925 an endless chain is used to periodically advance signatures through a stitcher. Pusher fingers connected with the chain extend through an opening formed along one side of the saddle. In U.S. Pat. No. 1,400,725 an opening is formed in one of the sides of the saddle and a mechanism reciprocates in the opening to advance the signatures. In these two conveyors a slot at the apex of the saddle between the two saddle faces receives a stationary stitching mechanism for stapling the signatures when they have been advanced to the proper position. There are several disadvantages to this system among which are the fact that the stitching operation is not performed "on the fly" and thus the signatures must be stopped and started.
U.S. Pat. No. 3,786,979 shows a design which permits access to the underside of the backbone of a signature and which provides a continuously moving stream of signatures on a conveyor. In the design disclosed in this patent two conveyor chains are disposed in a side by side arrangement. Each chain carries pusher pins to engage the back edges of a group of signatures and supports which support one side or leaf of the signature groups. Access from below to the backbone of the group of signatures for a stitcher assembly is provided by the gap between the conveyor chains. The stitcher is mounted on a reciprocating assembly to perform stitching on the fly.
Although this design enables the signature group to be stitched on the fly, the use of two chains is an expensive and unnecessary duplication. In addition, when the chains stretch, they do not stretch evenly and this causes pusher pins mounted to one chain to be ahead or behind the pins on the other chain.